Field of the invention
The present invention relate to wireless communication, and more particularly, to a method in which a terminal performs sidelink transmission in a wireless communication system, and the terminal using the method.
Related Art
In International Telecommunication Union Radio communication sector (ITU-R), a standardization task for International Mobile Telecommunication (IMT)-Advanced, that is, the next-generation mobile communication system since the third generation, is in progress. IMT-Advanced sets its goal to support Internet Protocol (IP)-based multimedia services at a data transfer rate of 1 Gbps in the stop and slow-speed moving state and of 100 Mbps in the fast-speed moving state.
For example, 3rd Generation Partnership Project (3GPP) is a system standard to satisfy the requirements of IMT-Advanced and is preparing for LTE-Advanced improved from Long Term Evolution (LTE) based on Orthogonal Frequency Division Multiple Access (OFDMA)/Single Carrier-Frequency Division Multiple Access (SC-FDMA) transmission schemes. LTE-Advanced is one of strong candidates for IMT-Advanced.
There is a growing interest in a Device-to-Device (D2D) technology in which devices perform direct communication. In particular, D2D has been in the spotlight as a communication technology for a public safety network. A commercial communication network is rapidly changing to LTE, but the current public safety network is basically based on the 2G technology in terms of a collision problem with existing communication standards and a cost. Such a technology gap and a need for improved services are leading to efforts to improve the public safety network.
The public safety network has higher service requirements (reliability and security) than the commercial communication network. In particular, if coverage of cellular communication is not affected or available, the public safety network also requires direct communication between devices, that is, D2D operation.
D2D operation may have various advantages in that it is communication between devices in proximity. For example, D2D UE has a high transfer rate and a low delay and may perform data communication. Furthermore, in D2D operation, traffic concentrated on a base station can be distributed. If D2D UE plays the role of a relay, it may also play the role of extending coverage of a base station.
Meanwhile, in LTE-A, a UE-to-UE interface is referred to as a sidelink. The sidelink may also be used in communication between UEs installed in vehicles or between a UE installed in a vehicle and another UE, that is, vehicle-to-everything (V2X).
However, when determining a resource used in V2X communication, there is a need to consider a subframe not suitable for performing V2X communication or a subframe for transmitting a V2X channel which has a relatively high priority and which must be protected from interference from another V2X signal.
In addition, when a resource that can be used in V2X communication is informed to a UE in a bitmap form, a reserved subframe may be configured to avoid ambiguity in indexing between the bitmap and subframes and to improve convenience. In this case, there is a need to specify how to configure the reserved subframe.